mitt romney in the state he was once governor, massachusetts. rick santorum is an ohio considered the biggest prize of all. >> the top two candidates both know they need big wins on super tuesday. mitt romney and rick santorum are urging voters to take nothing for granted. it is a tight race in the state that is being closely watched. >> with ohio polls showing a dead heat between mitt romney and rick santorum, the buckeye state is considered the biggest prize. >> we are going to win this thing. >> it is gut check time. who wants it the most. >> at stake, 10 states with more than 400 delegates. voters lined up early in a state also being closely watched -- tennessee. mitt romney wins a big win in the deep south. exit polls show this tight race could tip santorum. georgia has the most delegates up for grabs. it is newt gingrich's home turf. the main issue is how much can he win. he told voters he is still the best bet in november. >> i do think in terms of the republican nomination, i am the one person who could debate barack obama this fall. >>